In the field of large scale (250 gpm or greater) fire fighting nozzles, “fixed-flow” nozzles, in general, have long been traditional. A nozzle is “fixed-flow,” or is referred to as “fixed-flow,” when the nozzle discharge gap is fixed during use. The reference or term is used even when the discharge gap is selectively adjustable.
A nozzle discharge gap is typically the annular gap defined between a portion of a nozzle barrel and a nozzle bafflehead. One traditional adjustable fixed-flow nozzle design, for instance, permits the gap to be manually adjusted by screwing in and out a bafflehead located at the discharge end of the nozzle barrel.
In “fixed-flow” nozzles the flow rate, or gpm, varies with the square root of supplied fluid pressure. Although in practice there can be a significant variation in the fire fighting fluid supply pressure, variations which can run possibly +/−50%, the variation in the square root of that pressure is not great. Thus, the resulting variation in flow rate caused by a varying supply pressure is not too great. Thus, such nozzles, with the discharge gap fixed during flow, are referred to as “fixed-flow” nozzles.
(In contrast, by way of background, so called “automatic or “pressure regulating” nozzles automatically vary a nozzle discharge gap during use to attempt to maintain a pre-selected discharge pressure. Typically in such nozzles a bafflehead, assisting in defining the discharge gap, will be automatically adjusted to attempt to maintain a pre-selected discharge pressure. Since range tends to vary directly with pressure, “pressure regulating” nozzles tend to deliver fluid at a fixed range notwithstanding variations in supply pressure. Flow rate, however, in “pressure regulating” nozzles varies significantly. The flow rate varies with the variation in discharge gap used to target the discharge pressure. From this condition arises the contrast with “fixed-flow” nozzles. The instant invention is directed to improved “fixed-flow” nozzles.)
Additive, usually a foam or foaming concentrate, is frequently supplied to a fire fighting nozzle. It is designed by manufacturers to be proportioned into fire fighting fluid at a stated ratio, typically 1%, 3%, 6%, 10%. Various means have been developed in the industry to adapt for changing additive products during a job; that is, means have been developed to change from a product with one proportioning ratio to an additive product with another proportioning ratio. One such means has been the provision for the manual insertion of variable orifices in a flow path or line between an additive source and a nozzle. Small insertable orifices would be provided for additives designed to be mixed at lower ratios; larger orifices would be provided for additives designed to be mixed at higher ratios. Another variation, Klein U.S. Pat. No. 4,224,956, discloses a simple, manually adjustable proportioning valve, the valve adjustable between a set of stop positions, in order to proportion at different ratios.
The desire and/or ability to significantly adjust flow rate in a “fixed-flow” nozzle greatly complicates, however, this selection of a proper orifice. When flow rate can be widely adjusted, such as between 250 gpm and 500 gpm or greater, a selection of the proper orifice for proportioning additive, which is dependent upon flow rate (e.g. upon the adjusted size of the gap of the discharge,) becomes complex.
(In the field of “automatic” nozzles, discussed above, means have been invented [by the instant inventor] wherein an automatic variation in the discharge gap automatically provides a coordinated variation in a port in the additive fluid flow path, the variation being coordinated in two ways. One variation in port size is calibrated to automatically vary additive flow rate with variations in primary fluid flow rate caused by the nozzle's system of automatic adjustment. A second variation of port size is also calibrated to vary port size in accordance with a selected variation in the proportioning ratio of the additive. See co-pending patent application Ser. No. 10/677,900.)
The instant invention provides for a selectable “fixed flow” fire fighting nozzle with independently selectable, gap coordinated additive proportioning ratios. The additive proportioning ratios and flow rate selections are coordinated, but they are selectable independently of each other. That is, a fire fighter can select, independently, preferably by turning a dial, a flow rate and a proportioning ratio. A turn of the dial can select a different flow rate for the same proportioning ratio or a different proportioning ratio for the same flow rate, or both different. The instant invention provides a pre-calibrated orifice system, calibrated with a bafflehead adjustment system that controls discharge gap, such that bafflehead adjustment and additive orifice selection are independently selectable. For instance, if a nozzle provided for the selection between three flow rates and three additive ratios, then three bafflehead positions and nine orifice positions would be provided, one orifice position for each additive ratio at each flow rate. The orifice system lies in a fluid communication path between an additive source and the discharge end of the nozzle. To the best of applicant's knowledge, no prior art system has coordinated and cross calibrated a selection of nozzle-flow rates and a selection of additive ratio proportioning orifices.
The instant invention involves a further improvement. To the instant inventor's best knowledge, in the field of industrial-scale fire fighting nozzles, only very small nozzles have ever been offered in plastic either in whole or in part. These nozzles are typically referred to as “wash-down” nozzles in the industry. These nozzles offered in plastic have had a diameter of approximately 1½ inches or less and have been no longer than approximately 8 inches. Their flow rate has been less than 100 gpm. To date, plastics have not been used for critical parts of large industrial scale fire fighting nozzles. Industry concerns that have blocked the use of plastics in large industrial scale fire fighting nozzles include: (1) concern that plastics cannot sustain in general the high temperature of a fire and/or the high pressures of water, i.e. that their melting point and their yield strength is not sufficiently high; and (2) concern that plastics cannot sustain in general the high reaction loads such as the high thread stresses.
The instant inventor has determined, however, that as a material for constructing industrial scale fire fighting nozzles, plastics can offer significant cost and weight advantages. Plastics can be corrosion resistant and can include additives for controlling friction in order to facilitate sliding parts. Against the weight of tradition, the instant inventor therefore has experimented with the use of plastics for components of a preferred embodiment of a selectable fixed-flow, selectable additive proportioning, industrial scale fire fighting nozzle. The instant selectable fixed-flow, selectable proportioning nozzle, with complex inter related parts, offered an excellent test case for experimentation. Both the cost and the weight of an all metal nozzle could be ameliorated using lighter and cheaper plastic parts. Testing has proven that nozzle parts constructed of plastic can withstand the temperature, pressure and corrosion resistance required for the large industrial scale fire fighting nozzle. And as an added benefit, major customers for fire fighting nozzles include the major plastics manufacturers.